Search

The NOTCH signaling system regulates a variety of cellular processes during embryonic development and homeostasis maintenance in different tissues and contexts. Hence, dysregulation of NOTCH signaling is associated with a plethora of human cancers, and there have been multiple efforts to target key components of this pathway. In this review, we briefly highlight the latest research advances in understanding HES6, a poorly studied component of the NOTCH pathway. We summarize the role of HES6 in cancers with a focus on uveal melanoma. Finally, we discuss the ongoing efforts to target the NOTCH-HES6 axis in cancers.

Erratum inCorrection to: ITGBL1 is a new immunomodulator that favors development of melanoma tumors by inhibiting natural killer cells cytotoxicity.Cheli Y, Tulic MK, El Hachem N, Nottet N, Jacquel A, Gesson M, Strub T, Bille K, Picard-Gauci A, Montaudié H, Beranger GE, Passeron T, Close P, Bertolotto C, Ballotti R.Mol Cancer. 2021 Jan 27;20(1):21. doi: 10.1186/s12943-021-01319-5.PMID: 33504341 Free PMC article. No abstract available.; International audience; Resistances to immunotherapies remains a major hurdle towards a cure for melanoma in numerous patients. An increase in the mesenchymal phenotype and a loss of differentiation have been clearly associated with resistance to targeted therapies. Similar phenotypes have been more recently also linked to resistance to immune checkpoint therapies. We demonstrated here that the loss of MIcrophthalmia associated Transcription Factor (MITF), a pivotal player in melanocyte differentiation, favors the escape of melanoma cells from the immune system. We identified Integrin beta-like protein 1 (ITGBL1), a secreted protein, upregulated in anti-PD1 resistant patients and in MITFlow melanoma cells, as the key immunomodulator. ITGBL1 inhibited immune cell cytotoxicity against melanoma cells by inhibiting NK cells cytotoxicity and counteracting beneficial effects of anti-PD1 treatment, both in vitro and in vivo. Mechanistically, MITF inhibited RUNX2, an activator of ITGBL1 transcription. Interestingly, VitaminD3, an inhibitor of RUNX2, improved melanoma cells to death by immune cells. In conclusion, our data suggest that inhibition of ITGBL1 might improve melanoma response to immunotherapies.

Intratumor heterogeneity has been recognized in numerous cancers as a major source of metastatic dissemination. In uveal melanomas, the existence and identity of specific subpopulations, their biological function and their contribution to metastasis remain unknown. Here, in multiscale analyses using single-cell RNA sequencing of six different primary uveal melanomas, we uncover an intratumoral heterogeneity at the genomic and transcriptomic level. We identify distinct transcriptional cell states and diverse tumor-associated populations in a subset of the samples. We also decipher a gene regulatory network underlying an invasive and poor prognosis state driven in part by the transcription factor HES6. HES6 heterogenous expression has been validated by RNAscope assays within primary human uveal melanomas, which further unveils the existence of these cells conveying a dismal prognosis in tumors diagnosed with a favorable outcome using bulk analyses. Depletion of HES6 impairs proliferation, migration and metastatic dissemination in vitro and in vivo using the chick chorioallantoic membrane assay, demonstrating the essential role of HES6 in uveal melanomas. Thus, single-cell analysis offers an unprecedented view of primary uveal melanoma heterogeneity, identifies bona fide biomarkers for metastatic cells in the primary tumor, and reveals targetable modules driving growth and metastasis formation. Significantly, our findings demonstrate that HES6 is a valid target to stop uveal melanoma progression.

Uveal melanoma (UM) is an aggressive and deadly neoplasm. In recent decades, great efforts have been made to obtain a more comprehensive understanding of genetics, genomics and molecular changes in UM, enabling the identification of key cellular processes and signalling pathways. Still, there is no effective treatment for the metastatic disease. Intratumoural heterogeneity (ITH) is thought to be one of the leading determinants of metastasis, therapeutic resistance and recurrence. Crucially, tumours are complex ecosystems, where cancer cells, and diverse cell types from their microenvironment engage in dynamic spatiotemporal crosstalk that allows cancer progression, adaptation and evolution. This highlights the urgent need to gain insight into ITH in UM and its intersection with the microenvironment to overcome treatment failure. Here we provide an overview of the studies and technologies to study ITH in human UMs and tumour micro-environmental composition. We discuss how to incorporate ITH into clinical consideration for the purpose of advocating for new clinical management. We focus on the application of single-cell transcriptomic analysis and propose that understanding the driving forces and functional consequences of the observed tumour heterogeneity holds promise for changing the treatment paradigm of metastatic UMs, surmounting resistance and improving patient prognosis.

An amendment to this paper has been published and can be accessed via the original article.

International audience; BACKGROUND:MITF encodes an oncogenic lineage-specific transcription factor in which a germline mutation ( MITFE318K ) was identified in human patients predisposed to both nevus formation and, among other tumor types, melanoma. The molecular mechanisms underlying the oncogenic activity of MITF E318K remained uncharacterized.METHODS:Here, we compared the SUMOylation status of endogenous MITF by proximity ligation assay in melanocytes isolated from wild-type (n = 3) or E318K (n = 4) MITF donors. We also used a newly generated Mitf E318K knock-in (KI) mouse model to assess the role of Mitf E318K (n = 7 to 13 mice per group) in tumor development in vivo and performed transcriptomic analysis of the tumors to identify the molecular mechanisms. Finally, using immortalized or normal melanocytes (wild-type or E318K MITF, n = 2 per group), we assessed the role of MITF E318K on the induction of senescence mediated by BRAF V600E . All statistical tests were two-sided.RESULTS:We demonstrated a decrease in endogenous MITF SUMOylation in melanocytes from MITF E318K patients (mean of cells with hypoSUMOylated MITF, MITF E318K vs MITF WT , 94% vs 44%, difference = 50%, 95% CI = 21.8% to 67.2%, P = .004). The Mitf E318K mice were slightly hypopigmented (mean melanin content Mitf WT vs Mitf E318K/+ , 0.54 arbitrary units [AU] vs 0.36 AU, difference = -0.18, 95% CI = -0.36 to -0.007, P = .04). We provided genetic evidence that Mitf E318K enhances BRaf V600E -induced nevus formation in vivo (mean nevus number for Mitf E318K , BRaf V600E vs Mitf WT , BRaf V600E , 68 vs 44, difference = 24, 95% CI = 9.1 to 38.9, P = .006). Importantly, although Mitf E318K was not sufficient to cooperate with BRaf V600E alone in promoting metastatic melanoma, it accelerated tumor formation on a BRaf V600E , Pten-deficient background (median survival, Mitf E318K/+ = 42 days, 95% CI = 31 to 46 vs Mitf WT = 51 days, 95% CI = 50 to 55, P

International audience; In this paper we present three-dimensional numerical simulations of electromagnetic waves. The Maxwell equations are solved by the Discontinuous Galerkin (DG) method. For achieving high performance, we exploit two levels of parallelism. The coarse grain parallelism is managed through MPI and a classical domain decomposition. The fine grain parallelism is managed with OpenCL in order to optimize the local computations on multicore processors or GPU's. We present several numerical experiments and performance comparisons.; Dans cet article, nous présentons des simulations numériques tridimensionnelles d’ondes électromagnétiques. Les équations de Maxwell sont résolues par la méthode de Galerkin Discontinue (GD). Pour accélérer les calculs, nous exploitons deux niveaux de parallélisme. Le large grain est basé sur MPI. Le parallélisme à grain fin repose sur OpenCL afin d’exploiter les processeurs massivement multicoeur (GPU ou CPU) récents. Nous présentons plusieurs expériences numériques et des tests de performance.

Nature 480, 94–98 (2011); doi:10.1038/nature10539 In this Letter, one image was mistakenly duplicated during preparation of the artwork. In the original Fig. 3d, the left image illustrating migration of RCC4 cells transduced with empty adenovirus (EV) at 24 h is a duplicate of the middle image showing migration of RCC4 cells transduced with an adenovirus encoding Mi-WT.

Recent experiments using the Crystal Ball/TAPS setup at the MAMI accelerator in Mainz, Germany, continue to study the properties and the excitation spectrum of the nucleon with meson photoproduction. Electromagnetic excitations of the proton and neutron are essential for understanding their isospin decomposition. The electromagnetic coupling of photons to protons is different than that to neutrons in certain states. Hence, a complete partial wave analysis (PWA) can assist in yielding more information about any reaction, but requires the determination of polarization observables. Polarization observables play a crucial role as they are essential in disentangling the contributing resonant and non-resonant amplitudes, whereas cross section data alone is not sufficient for separating broad overlapping resonances. Preliminary results of polarization observables of η, single, and double π production off a polarized neutron (dButanol) target will be shown with comparison to predictions of recent multipole analyses. These results will greatly increase the world database on pseudoscalar meson production on neutrons.

MIcrophthalmia-associated Transcription Factor (MITF) regulates melanocyte and melanoma physiology. We show that MITF associates the NURF chromatin-remodelling factor in melanoma cells. ShRNA-mediated silencing of the NURF subunit BPTF revealed its essential role in several melanoma cell lines and in untransformed melanocytes in vitro. Comparative RNA-seq shows that MITF and BPTF co-regulate overlapping gene expression programs in cell lines in vitro. Somatic and specific inactivation of Bptf in developing murine melanoblasts in vivo shows that Bptf regulates their proliferation, migration and morphology. Once born, Bptf-mutant mice display premature greying where the second post-natal coat is white. This second coat is normally pigmented by differentiated melanocytes derived from the adult melanocyte stem cell (MSC) population that is stimulated to proliferate and differentiate at anagen. An MSC population is established and maintained throughout the life of the Bptf-mutant mice, but these MSCs are abnormal and at anagen, give rise to reduced numbers of transient amplifying cells (TACs) that do not express melanocyte markers and fail to differentiate into mature melanin producing melanocytes. MSCs display a transcriptionally repressed chromatin state and Bptf is essential for reactivation of the melanocyte gene expression program at anagen, the subsequent normal proliferation of TACs and their differentiation into mature melanocytes., Author Summary The melanocytes pigmenting the coat of adult mice derive from the melanocyte stem cell population residing in the permanent bulge area of the hair follicle. At each angen phase, melanocyte stem cells are stimulated to generate proliferative transient amplifying cells that migrate to the bulb of the follicle where they differentiate into mature melanin producing melanocytes, a processes involving MIcrophthalmia-associated Transcription Factor (MITF) the master regulator of the melanocyte lineage. We show that MITF associates with the NURF chromatin-remodelling factor in melanoma cells. NURF acts downstream of MITF in melanocytes and melanoma cells co-regulating gene expression in vitro. In vivo, mice lacking the NURF subunit Bptf in the melanocyte lineage show premature greying as they are unable to generate mature melanocytes from the adult stem cell population. We find that the melanocyte stem cells from these animals are abnormal and that once they are stimulated at anagen, Bptf is required to ensure the expression of melanocyte markers and their differentiation into mature adult melanocytes. Chromatin remodelling by NURF therefore appears to be essential for the transition of the transcriptionally quiescent stem cell to the differentiated state.

Histone variants are emerging as key regulatory molecules in cancer. We report a unique role for the H2A.Z isoform H2A.Z.2 as a driver of malignant melanoma. H2A.Z.2 is highly expressed in metastatic melanoma, correlates with decreased patient survival, and is required for cellular proliferation. Our integrated genomic analyses reveal that H2A.Z.2 controls the transcriptional output of E2F target genes in melanoma cells. These genes are highly expressed and display a distinct signature of H2A.Z occupancy. We identify BRD2 as an H2A.Z-interacting protein, levels of which are also elevated in melanoma. We further demonstrate that H2A.Z.2-regulated genes are bound by BRD2 and E2F1 in an H2A.Z.2-dependent manner. Importantly, H2A.Z.2 deficiency sensitizes melanoma cells to chemotherapy and targeted therapies. Collectively, our findings implicate H2A.Z.2 as a mediator of cell proliferation and drug sensitivity in malignant melanoma, holding translational potential for novel therapeutic strategies.

Meson photoproduction has developed into a powerful tool to study the nu- cleon excitation spectrum and test effective quark models which operate in the non- perturbative regime of QCD. An insight into the J P configurations and isospin decom- positions of the contributing resonances is gained by measuring a minimal set of polar- ization observables on both the proton and the neutron. Single π 0 - and η-photoproduction off a transversally polarized d-butanol target has been measured with circularly polarized bremsstrahlung photons generated by the MAMI-C electron microtron. With the nearly 4π acceptance of the combined Crystal Ball/TAPS setup the double polarization observable F and the target asymmetry T can be extracted for the first time for polarized, quasi-free neutrons over a wide energy and angular range.

Malignant melanoma is one of the most aggressive human cancers. Metastatic melanoma is highly resistant to genotoxic radiotherapy and chemotherapeutic treatments and patients have a median survival of under a year from diagnosis. As primary melanoma tumours can metastasise very early in tumour development (Chin et al., 2006), rapid diagnosis and curative surgery remain the best hopes for control of the disease. Early surgery that removes radial growth phase tumours that have not yet initiated vertical growth phase can be very effective and prevent further development. However, once the primary tumour has begun to invade the local epidermal and dermal environment treatment becomes much more complicated Why melanoma has such a high propensity to invade and metastasize is not well understood, but may be related to the developmental characteristics of the melanocyte lineage. Melanocytes derive from pluripotent neural crest cells as non-pigmented melanoblasts (Dupin et al., 2007; Dupin et al., 2006; Thomas and Erickson, 2008). During embryogenesis melanoblasts migrate via the dorso-lateral pathway to populate the basal layer of the epidermis and hair follicles, as well as a number of other sites including the inner ear and the heart (Yajima and Larue, 2008). The ability of transformed melanoma cells to rapidly invade and migrate away from the primary tumour perhaps reflects an inherent characteristic inherited from their embryonic state. Neural crest-derived cells are specified as melanoblasts by expression of MIcrophthalmiaassociated Transcription Factor (MITF), a basic helix-loop-helix transcription factor belonging to the MYC superfamily (Goding, 2000a; Goding, 2000b; Hemesath et al., 1994). The MITF locus encodes multiple isoforms generated by alternate splicing and use of internal promoters (Steingrimsson, 2008). The MITF-M isoform (hereafter designated simply as MITF) is produced specifically in the melanocyte lineage from an intronic promoter. MITF is required for melanoblast survival and differentiation of the retinal pigment epithelium (RPE) (Hou and Pavan, 2008; McGill et al., 2002). Consequently, MITF-null mice exhibit a white coat colour due to the loss of the melanocyte lineage and a small (microphthalmic) eye phenotype due to loss of the RPE (Hodgkinson et al., 1993; Hughes et al., 1993; Moore, 1995; Steingrimsson et al., 1994). In humans, mutation of the MITF gene is responsible for Waardenburg syndrome type 2 (WS2) ((Tassabehji et al., 1994), a syndrome characterised by pigmentary defects and hearing loss highlighting the important role of the

Comment inCommentary. A picture of Mitf in melanoma immortality. [Oncogene. 2011]; International audience; Malignant melanoma is an aggressive cancer known for its notorious resistance to most current therapies. The basic helix-loop-helix microphthalmia transcription factor (MITF) is the master regulator determining the identity and properties of the melanocyte lineage, and is regarded as a lineage-specific 'oncogene' that has a critical role in the pathogenesis of melanoma. MITF promotes melanoma cell proliferation, whereas sustained supression of MITF expression leads to senescence. By combining chromatin immunoprecipitation coupled to high throughput sequencing (ChIP-seq) and RNA sequencing analyses, we show that MITF directly regulates a set of genes required for DNA replication, repair and mitosis. Our results reveal how loss of MITF regulates mitotic fidelity, and through defective replication and repair induces DNA damage, ultimately ending in cellular senescence. These findings reveal a lineage-specific control of DNA replication and mitosis by MITF, providing new avenues for therapeutic intervention in melanoma. The identification of MITF-binding sites and gene-regulatory networks establish a framework for understanding oncogenic basic helix-loop-helix factors such as N-myc or TFE3 in other cancers.

Malignant melanoma is the most lethal form of skin cancer with rising incidence. Once metastasis occurs, patients have a dismal prognosis, largely due to limited systemic treatment with chemotherapy and resistance to targeted therapies. Thus, effective therapies with long-term responses are currently lacking. Although much effort has focused on characterizing and targeting the genetic alterations in melanoma, the identification of epigenetic players remains poorly understood. Chromatin dynamics have recently been shown to exert a critical function in a number of cancers, including melanoma, and emerging evidence points towards a role of histone variants as key regulatory molecules in cancer. H2A.Z is a highly conserved H2A variant, harboring two different isoforms in vertebrates, H2A.Z.1 and H2A.Z.2. High levels of H2A.Z promote cell proliferation in breast, prostate and bladder cancers, however studies so far have focused primarily on H2A.Z.1 or did not clearly distinguish between the two isoforms. Here, we report a role for the unappreciated isoform H2A.Z.2 as a mediator of cell proliferation and drug sensitivity in malignant melanoma. To our knowledge, this is the first evidence to implicate a distinct role for this H2A.Z isoform in any tumor type. While both H2A.Z.1 and H2A.Z.2 are highly expressed in metastatic melanoma and correlate with decreased patient survival, only H2A.Z.2 deficiency results in impaired cellular proliferation, which occurs through a G1 to S arrest. Integrated gene expression and ChIP-seq analyses revealed that H2A.Z.2 positively regulates E2F target genes, which are highly expressed and acquire a distinct H2A.Z occupancy signature over the promoter and gene body in metastatic cells. We further identified the BET (bromodomain and extraterminal domain) family member BRD2 as an H2A.Z-interacting protein in melanoma cells, and our data suggest that H2A.Z.2 exerts its oncogenic function by maintaining the global levels of BRD2 and histone H4 acetylation. Furthermore, H2A.Z.2 depletion sensitizes melanoma cells to targeted therapies and chemotherapy. Collectively, our findings implicate H2A.Z.2 as a driver of melanoma pathogenesis. Owing to the fact that histone modification is a reversible process, H2A.Z.2 and BRD2 hold translational potential for novel therapeutic strategies. Citation Format: Chiara Vardabasso, Alexandre Gaspar-Maia, Sebastian Punzeler, David Valle-Garcia, Dan Hasson, Tobias Straub, Eva C. Keilhauer, Thomas Strub, Taniya Panda, Miguel F. Segura, Chi-Yeh Chung, Amit K. Verma, Matthias Mann, Eva Hernando, Sandra B. Hake, Emily Bernstein. Histone variant H2A.Z.2 mediates proliferation and drug sensitivity of malignant melanoma. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Melanoma: From Biology to Therapy; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(14 Suppl):Abstract nr A12.

Publisher's version (útgefin grein), It is widely assumed that decreasing transcription factor DNA-binding affinity reduces transcription initiation by diminishing occupancy of sequence-specific regulatory elements. However, in vivo transcription factors find their binding sites while confronted with a large excess of low-affinity degenerate motifs. Here, using the melanoma lineage survival oncogene MITF as a model, we show that low-affinity binding sites act as a competitive reservoir in vivo from which transcription factors are released by mitogen-activated protein kinase (MAPK)-stimulated acetylation to promote increased occupancy of their regulatory elements. Consequently, a low-DNA-binding-affinity acetylation-mimetic MITF mutation supports melanocyte development and drives tumorigenesis, whereas a high-affinity non-acetylatable mutant does not. The results reveal a paradoxical acetylation-mediated molecular clutch that tunes transcription factor availability via genome-wide redistribution and couples BRAF to tumorigenesis. Our results further suggest that p300/CREB-binding protein-mediated transcription factor acetylation may represent a common mechanism to control transcription factor availability., The Piggybac vectors were provided by Kazuhiro Murakami (RIKEN, Kobe, Japan). This work was funded by the Ludwig Institute for Cancer Research (C.R.G., R.F., B.S.-B., E. Suer, and X.L. ), Cancer Research UK (CRUK) grant number C38302/A12981 , through a CRUK Oxford Centre Prize DPhil Studentship (HF), the Medical Research Council (R.S., Z.Z., P.F.; MR/N010051/1 and E.E.P.; MC_UU_00007/9 ), L’Oreal-Melanoma Research Alliance 401181 (E.E.P.), the Harry J. Lloyd Trust (R.S.), the Wellcome Trust (P.F. and A.S.), the Postdoc Fund of the University of Iceland (A.S.), the Oxford Biomedical Research Centre (R.L.), the Research Fund of Iceland (E.S.), a European Research Consolidator Award ( ZF-MEL-CHEMBIO 648489 ) (E.E.P.), the CNRS , INSERM , the Ligue Nationale Contre le Cancer , the Institut National du Cancer ( INCa ), the ANR-10-LABX-0030-INRT French state fund (I.D.), and a Junior 1 salary award from the Fonds de Recherche du Québec-Santé ( FRQ-S ). This work was also funded by operating grants from the Cancer Research Society (J.-P.L.), the Fondazione Cariplo (A.L. and D.M.; 2014-1157 ), and the Italian Cancer Research Association ( AIRC ; IG2018- 21897 ; D.M.). I.D. is an “équipe labellisée” of the Ligue Nationale Contre le Cancer .